1. Field of the Invention
The invention relates to a respirator with a module that includes a speech transmission and exhalation valve functions. In one of its aspects, the invention relates to a respirator module incorporating an exhalation valve, a speech transmitter and a drinking tube. In another of its aspects, the invention relates to a respirator speech transmission module with integral electrical connections for communications devices. In another of its aspects, the invention relates to a respirator with a speech transmission and an exhalation valve module. In yet another of its aspects, the invention relates to a respirator and speech transmitter module therefore with low airflow resistance through the module.
2. Description of the Related Art
When a respirator such as a gas mask is used in a contaminated environment, it is critical that the wearer only inhale air from a purified source or air that has been passed through a filtration canister. In the typical gas mask having removable filtration canisters, the filtration canisters are attached to a filter mount including an inhalation valve that provides for one-way flow, opening during inhalation and closing during exhalation to prevent exhalation of hot, moisture-laden air through the filter.
It is important that the inhalation valve introduce no restrictions in the airflow path that will put additional strains on the wearer. In like fashion, it is important that an exhalation valve has minimal restrictions in the exhalation airflow but has secure sealing during inhalation. As the inhalation valve must have a low-opening pressure, the exhalation valve must also have a low-opening pressure to reduce the burden on the wearer and the likelihood of breaking the seal of the respirator.
Further, it is important that the wearer has the ability to communicate clearly with others in the vicinity or by radio while the respirator is in place and functioning in the contaminated environment. It is therefore advantageous for an exhalation module to have low-resistance opening during wearer exhalation, complete sealing during wearer inhalation and with high intelligibility of wearer speech.
U.S. Pat. No. 4,958,633, issued Sep. 25, 1990, to Angell, discloses a respirator with a speech and exhalation module incorporating an elastomeric exhalation valve. The exhalation valve is constructed of resilient material in a generally dished form anchored at a central portion and adapted to seal on a peripheral edge onto a valve seat on the module housing. The exhalation valve has an annular channel, formed by an annular arcuate section and that faces the outside of the mask. The module forms an air path in the form of an exponential horn between the inside and outside of the mask. The air path reverses axial direction between the inlet and the outlet, creating some turbulence. The speech module and exhalation valve have a fairly low resistance to exhalation, in the range of about 15 mm at 85 l/min air flow. The respirator also has interchangeable mountings on the face piece for a secondary speech outlet, such as a microphone, and for an air-purifying canister. The speech transmitter module is disclosed more fully in the U.S. Pat. No. 4,539,983, issued Sep. 10, 1985, to Angell. These two Angell patents are incorporated herein by reference in their entirety.